<!DOCTYPE html>
<html lang="zh-CN">
    <head>
        <title>task4</title>
        <meta charset="UTF-8">
        <link href="style.css" rel="stylesheet">
    </head>
    <body>
        <div class="box">
            <div class="c1"></div>
            <div class="c2"></div>
        </div>
    </body>
</html>